Fermented Vegetables for Gut Health

Overseen By Danielle G Lemay, PhD

Age: 18+

Sex: Any

Trial Phase: Academic

Sponsor: USDA, Western Human Nutrition Research Center

Must not be taking: Immunosuppressants, Biologics, Antidiabetics, Diuretics

Disqualifiers: Hypertension, Diabetes, Cancer, Auto-immune, others

No Placebo Group All trial participants will receive the active study treatment (no placebo)

Compensation: Varies

Number of Visits: 3

24 Participants Needed

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial aims to assess how eating fermented vegetables affects gut health, focusing on the presence of beneficial bacteria. Initially, the trial will evaluate the response in young, healthy adults before including older participants. Participants will begin without any fermented foods, consume fermented vegetables for four days, and then stop again. Those with conditions like asthma or diabetes requiring daily medication, or those who regularly consume fermented foods or probiotics, are not suitable candidates. Individuals with at least three bowel movements a week and no recent surgeries or major illnesses might be eligible to join. As an unphased study, this trial offers a unique opportunity to contribute to understanding the benefits of fermented foods on gut health.

Will I have to stop taking my current medications?

The trial excludes participants who have used certain medications recently, such as antibiotics, antifungals, antivirals, and some immune system drugs. If you are taking these or similar medications, you may not be eligible to participate.

What prior data suggests that fermented vegetables are safe for consumption?

Research has shown that fermented foods, such as vegetables, are usually safe and beneficial for gut health. Studies indicate they can increase the variety of good bacteria in the gut, which links to better overall health. Consuming fermented foods safely introduces more beneficial bacteria to the system, potentially improving gut health and reducing certain health risks.

However, some safety points require consideration. During production, fermented vegetables can sometimes develop substances like biogenic amines and nitrite and may encounter microbial issues. Proper preparation and storage usually control these concerns.

Overall, fermented vegetables are widely regarded as healthy and safe. They are a common part of diets worldwide, and participants in previous studies have generally tolerated them well. ^{1 2 3 4 5}

Why are researchers excited about this trial?

Fermented vegetables are unique because they promote gut health through natural probiotics, which are beneficial bacteria that can enhance digestion and boost the immune system. Unlike standard treatments for gut health, which often involve supplements or medications like probiotics in pill form, fermented vegetables offer a food-based approach that integrates easily into daily diets. Researchers are excited about this treatment because it has the potential to improve gut health quickly, with noticeable effects in just a few days, and it harnesses the power of natural fermentation, which is a time-tested process for enhancing nutritional benefits.

What evidence suggests that fermented vegetables might be an effective treatment for gut health?

Research has shown that eating fermented vegetables benefits gut health. One study found that a diet high in fermented foods increases gut bacteria diversity, aiding the immune system and reducing inflammation. Another study found that consuming fermented vegetables like carrots and kimchi improved various health measures. Regularly eating these foods affects how the gut processes food more than it changes the bacteria itself. Additionally, fermented pickles have improved gut bacteria, enhancing overall gut health. These findings suggest that fermented vegetables help maintain a healthy digestive system. Participants in this trial will undergo a 4-day fermented vegetable intervention to explore these benefits further. ^{1 6 7 8 9}

Who Is on the Research Team?

Bess L Caswell, PhD

Principal Investigator

USDA, Western Human Nutrition Research Center

Danielle G Lemay, PhD

Principal Investigator

USDA, Western Human Nutrition Research Center

Mary E Kable, PhD

Principal Investigator

USDA, Western Human Nutrition Research Center

Are You a Good Fit for This Trial?

This trial is for young, healthy individuals interested in the effects of fermented vegetables on gut health. Specific eligibility criteria are not provided, but typically participants should have no major health issues that could interfere with the study.

Inclusion Criteria

BMI between 18.5 and 39.9 kg/m2

Exclusion Criteria

Consumption of probiotic supplements, foods, or drinks in the past month

My blood pressure is not higher than 140/90 mmHg.

Pregnant or breastfeeding individuals

Timeline for a Trial Participant

Baseline

Participants complete a 1-week baseline with no fermented food intake

1 week

1 visit (in-person)

Intervention

Participants consume fermented vegetables for 4 days

4 days

1 visit (in-person)

Follow-up

Participants undergo a 1-week follow-up period with no fermented food intake

1 week

1 visit (in-person)

What Are the Treatments Tested in This Trial?

Interventions

• Fermented Vegetables

Trial Overview The study investigates how eating fermented vegetables affects beneficial bacteria (LAB) in the gut and how well people tolerate this diet change. It's a preliminary step before a larger trial targeting older adults.

How Is the Trial Designed?

Group I: Fermented vegetable consumption Experimental Treatment 1 Intervention

Participants will complete a 1-week baseline with no fermented food intake, followed by a 4-day fermented vegetable intervention, and then a 1-week follow-up period with no fermented food intake.

Who Is Running the Clinical Trial?

USDA, Western Human Nutrition Research Center

Lead Sponsor

Trials

64

Recruited

19,100+

Published Research Related to This Trial

Lactic acid fermentation, especially when combined with germinated cereals, can enhance the nutritional quality and safety of weaning foods by providing high nutrient density and antimicrobial properties.

The workshop identified key research priorities, including understanding the effects of fermentation on harmful microorganisms and mycotoxins, optimizing fermentation processes, and improving food safety practices for better consumer acceptance of fermented foods.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Food fermentation: a safety and nutritional assessment. Joint FAO/WHO Workshop on Assessment of Fermentation as a Household Technology for Improving Food Safety. Motarjemi, Y., Nout, MJ.[2022]

Fermentation processes, both in food production and the gastrointestinal tract, produce compounds that can significantly impact consumer health, highlighting the importance of selecting specific food-fermenting microbes to enhance nutritional value.

The gut microbiota plays a crucial role in generating health-active molecules, and dietary choices can modulate this activity, suggesting that a multidisciplinary approach is essential for understanding how diet and microbes interact to benefit health.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Impact of microbial transformation of food on health - from fermented foods to fermentation in the gastro-intestinal tract. van Hylckama Vlieg, JE., Veiga, P., Zhang, C., et al.[2011]

Fermented foods, like yogurt and kimchi, not only improve shelf life and safety but also enhance nutritional value and functional properties due to the transformation of their ingredients during fermentation.

Emerging evidence suggests that fermented foods may offer health benefits beyond their original ingredients, potentially due to the presence of live microorganisms similar to probiotics.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Health benefits of fermented foods: microbiota and beyond. Marco, ML., Heeney, D., Binda, S., et al.[2018]

Kefir is the most studied fermented food, showing potential benefits for lactose malabsorption and eradicating Helicobacter pylori based on randomized controlled trials (RCTs).

Overall, there is limited clinical evidence supporting the health benefits of most fermented foods for gastrointestinal health, highlighting the need for more high-quality clinical trials despite promising in vitro results.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Fermented Foods: Definitions and Characteristics, Impact on the Gut Microbiota and Effects on Gastrointestinal Health and Disease. Dimidi, E., Cox, SR., Rossi, M., et al.[2021]

Fermented foods have been part of human diets for nearly 10,000 years and contain unique microorganisms that can positively influence gut health.

These foods can impact the gut microbiome both in the short and long term, making them an important component of a healthy diet.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Fermented Foods, Health and the Gut Microbiome. Leeuwendaal, NK., Stanton, C., O'Toole, PW., et al.[2022]

Citations

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Fermented Foods, Health and the Gut Microbiome - PMC This review clearly shows that fermented foods can affect the gut microbiome in both the short and long term, and should be considered an important element of ...

2. med.stanford.edu med.stanford.edu/news/all-news/2021/07/fermented-food-diet-increases-microbiome-diversity-lowers-inflammation.html

Fermented-food diet increases microbiome diversity ... Stanford researchers discover that a 10-week diet high in fermented foods boosts microbiome diversity and improves immune responses.

3. frontiersin.org frontiersin.org/journals/nutrition/articles/10.3389/fnut.2025.1623710/full

Impact of fresh and fermented vegetable consumption on ... This study evaluated the effects of fermented vegetables (FVs) intake including fermented carrots, kohlrabi, and kimchi on human health parameters

4. sciencedirect.com sciencedirect.com/science/article/pii/S0149763424000307

Fermented foods: Harnessing their potential to modulate ... Regular consumption of lacto-fermented vegetables has greater effects on the gut metabolome compared with the microbiome. Gut Micro, 4 (2023), Article e11.

5. nature.com nature.com/articles/s41598-025-17721-8

Fermented pickles improve gut microbiota and immune ... Gut microbiota-targeted diets like fermented foods have the potential to improve the gut microbiome Our study highlights the first ...

6. nature.com nature.com/articles/s41575-023-00869-x

Fermented foods and gastrointestinal health: underlying ... Fermented foods represent a safe way for increased microbial exposure with a view to improving gut health and potentially reducing the risk of ...

7. sciencedirect.com sciencedirect.com/science/article/pii/S2161831325000481

Unpacking Food Fermentation: Clinically Relevant Tools ... Fermented foods have been associated with increased gut microbiome diversity and resilience, which are linked to better overall health. Diverse health benefits ...

8. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC10777956/

Fermented Vegetables: Health Benefits, Defects, and ... Three main safety problems occurred in different stages of fermented vegetable production (Figure 4): biogenic amine, nitrite, and microbial safety.

9. frontiersin.org frontiersin.org/journals/nutrition/articles/10.3389/fnut.2024.1458536/full

Health benefits and risks of fermented foods—the ... Worldwide, fermented foods (FF) are recognized as healthy and safe. Despite the rapid increase of research papers, there is a lack of systematic evaluation ...